The electrical companies usually place at least one meter at the junction of the main distribution power lines with their customer consumption location, that it be a factory, a house, a shop, a business, or a residential building, thereby to collectively monitor the kilowatts drawn from the main AC lines on the basis of the sensed voltage and current, and to compute the energy so as to bill the customer according to actual demand. It is now proposed to determine at the customer's level how much at a sublevel has been consumed, behind such an electrical meter of the utility company, at each of the sublocations of users in order that the billing can be divided and the cost fairly distributed between them, that they be residents, tenants, workshop craftsmen, or shopkeepers.
It is known from U.S. Pat. No. 4,168,491 to control the demand of energy consumed by several users pertaining to a common building. The purpose, there, is to stop the user's consumption whenever it exceeds a predetermined limit. To this effect, when power may be exceeded, from a central location all the users in the group are distributively switched OFF, either cyclically and for a certain duration, or told to switch OFF.
It is known from U.S. Pat. No. 3,937,978 to control remotely electrical loads, such as multi-unit lodging establishments, power sensing being used to deenergize a load having excessive consumption.
From U.S. Pat. No. 3,906,242 it is known to monitor loads under programmed peak load reduction from a computer load center operating with a signal transmitter upon a plurality of installations having their local signal receiver and load limiter.
U.S. Pat. No. 4,090,062 shows an energy demand controller for a house, or a building, having separated heaters and appliances, each having a local control unit and an intermediary switch.
In U.S. Pat. No. 4,100,426 load controlling is accomplished with plug-in modules which are part of a standard package associated with the respective loads for a given installation.
With U.S. Pat. No. 4,206,443 protective load disconnection is remotely performed at a single control input terminal from a master controller and monitoring unit.
U.S. Pat. No. 4,874,926 discloses the use of low voltage thermal relays placed adjacent to the downstream or outlet side of a residential circuit breaker n the in-residence power distribution lines leading to individual electrical heating elements.
U.S. Pat. No. 4,164,719 is for a load management application wherein, between the local load and the power input, a conventional circuit breaker is combined with a management module.
U.S. Pat. No. 4,178,572 is like the '719 patent but with a contactor-circuit breaker arranged for mounting in the same panelboard having the load circuit breaker serving for energization.
U.S. Pat. No. 4,308,511 relates to a load management circuit breaker containing an electronic package and a remote-controlled switch, associated with an electric energy meter and a master control transmitter connected through a line of communication.
Complementary to the '511 patent, in U.S. Pat. No. 4,130,874 is described a power line communication system with selectable address formats.
Digital processing for producing signals representative of electrical energy parameters, in a system like shown in the '511 and '874 patents, is described by U.S. Pat. No. 4,077,061.
U.S. Pat. No. 4,806,855 relates to a system for rating electric power transmission lines. The system there described includes current sensor-transmitter for multiplexed transmission by telecommunication-link to a computer.
U.S. Pat. No. 4,219,860 shows digital overcurrent relay apparatus using sampling with digital conversion in relation to the monitored AC current.
In U.S. Pat. No. 4,423,459 a solid state circuit is illustrated involving AC current monitoring by sampling and digital conversion.
In U.S. Pat. No. 4,682,264 a microprocessor-based solid-state trip unit processes digital signals derived from current sensors.
Digital power metering with voltage and current samples is shown in U.S. Pat. No. 4,884,021.
It is known from U.S. Pat. No. 4,689,752, from U.S. Pat. No. 4,799,005 and from U.S. Pat. No. 4,855,671 to perform metering functions with high speed sampling at several local stations and to transmit the information to a common remote station.
It is known from U.S. Pat. No. 4,933,633 to effectuate energy monitoring with a communication channel between a central station and several remote stations.
From U.S. Pat. No. 4,692,761, a communication system is known including a master unit and several remote units with transfer of data relating to power consumption from one remote unit to the master unit.